feat: Enable REST transport for most of Java and Go clients

google-cloud-datastream/pom.xml

@@ -64,6 +64,10 @@
     <dependency>
       <groupId>com.google.api</groupId>
       <artifactId>gax-grpc</artifactId>
+    </dependency>
+     <dependency>
+      <groupId>com.google.api</groupId>
+      <artifactId>gax-httpjson</artifactId>
     </dependency>
     <dependency>
       <groupId>org.threeten</groupId>
@@ -89,12 +93,24 @@
       <scope>test</scope>
     </dependency>
     <!-- Need testing utility classes for generated gRPC clients tests -->
+     <dependency>
+      <groupId>com.google.api</groupId>
+      <artifactId>gax</artifactId>
+      <classifier>testlib</classifier>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>com.google.api</groupId>
       <artifactId>gax-grpc</artifactId>
       <classifier>testlib</classifier>
       <scope>test</scope>
     </dependency>
+    <dependency>
+    <groupId>com.google.api</groupId>
+      <artifactId>gax-httpjson</artifactId>
+      <classifier>testlib</classifier>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <profiles>

google-cloud-datastream/src/main/java/com/google/cloud/datastream/v1/DatastreamClient.java

@@ -19,6 +19,7 @@
 import com.google.api.core.ApiFuture;
 import com.google.api.core.ApiFutures;
 import com.google.api.gax.core.BackgroundResource;
+import com.google.api.gax.httpjson.longrunning.OperationsClient;
 import com.google.api.gax.longrunning.OperationFuture;
 import com.google.api.gax.paging.AbstractFixedSizeCollection;
 import com.google.api.gax.paging.AbstractPage;
@@ -34,7 +35,6 @@
 import com.google.cloud.location.Location;
 import com.google.common.util.concurrent.MoreExecutors;
 import com.google.longrunning.Operation;
-import com.google.longrunning.OperationsClient;
 import com.google.protobuf.Empty;
 import com.google.protobuf.FieldMask;
 import java.io.IOException;
@@ -107,13 +107,28 @@
  * DatastreamClient datastreamClient = DatastreamClient.create(datastreamSettings);
  * }</pre>
  *
+ * <p>To use REST (HTTP1.1/JSON) transport (instead of gRPC) for sending and receiving requests over
+ * the wire:
+ *
+ * <pre>{@code
+ * // This snippet has been automatically generated for illustrative purposes only.
+ * // It may require modifications to work in your environment.
+ * DatastreamSettings datastreamSettings =
+ *     DatastreamSettings.newBuilder()
+ *         .setTransportChannelProvider(
+ *             DatastreamSettings.defaultHttpJsonTransportProviderBuilder().build())
+ *         .build();
+ * DatastreamClient datastreamClient = DatastreamClient.create(datastreamSettings);
+ * }</pre>
+ *
  * <p>Please refer to the GitHub repository's samples for more quickstart code snippets.
  */
 @Generated("by gapic-generator-java")
 public class DatastreamClient implements BackgroundResource {
   private final DatastreamSettings settings;
   private final DatastreamStub stub;
-  private final OperationsClient operationsClient;
+  private final OperationsClient httpJsonOperationsClient;
+  private final com.google.longrunning.OperationsClient operationsClient;
 
   /** Constructs an instance of DatastreamClient with default settings. */
   public static final DatastreamClient create() throws IOException {
@@ -143,13 +158,17 @@ public static final DatastreamClient create(DatastreamStub stub) {
   protected DatastreamClient(DatastreamSettings settings) throws IOException {
     this.settings = settings;
     this.stub = ((DatastreamStubSettings) settings.getStubSettings()).createStub();
-    this.operationsClient = OperationsClient.create(this.stub.getOperationsStub());
+    this.operationsClient =
+        com.google.longrunning.OperationsClient.create(this.stub.getOperationsStub());
+    this.httpJsonOperationsClient = OperationsClient.create(this.stub.getHttpJsonOperationsStub());
   }
 
   protected DatastreamClient(DatastreamStub stub) {
     this.settings = null;
     this.stub = stub;
-    this.operationsClient = OperationsClient.create(this.stub.getOperationsStub());
+    this.operationsClient =
+        com.google.longrunning.OperationsClient.create(this.stub.getOperationsStub());
+    this.httpJsonOperationsClient = OperationsClient.create(this.stub.getHttpJsonOperationsStub());
   }
 
   public final DatastreamSettings getSettings() {
@@ -164,10 +183,18 @@ public DatastreamStub getStub() {
    * Returns the OperationsClient that can be used to query the status of a long-running operation
    * returned by another API method call.
    */
-  public final OperationsClient getOperationsClient() {
+  public final com.google.longrunning.OperationsClient getOperationsClient() {
     return operationsClient;
   }
 
+  /**
+   * Returns the OperationsClient that can be used to query the status of a long-running operation
+   * returned by another API method call.
+   */
+  public final OperationsClient getHttpJsonOperationsClient() {
+    return httpJsonOperationsClient;
+  }
+
   // AUTO-GENERATED DOCUMENTATION AND METHOD.
   /**
    * Use this method to list connection profiles created in a project and location.

google-cloud-datastream/src/main/java/com/google/cloud/datastream/v1/DatastreamSettings.java

@@ -29,6 +29,7 @@
 import com.google.api.gax.core.GoogleCredentialsProvider;
 import com.google.api.gax.core.InstantiatingExecutorProvider;
 import com.google.api.gax.grpc.InstantiatingGrpcChannelProvider;
+import com.google.api.gax.httpjson.InstantiatingHttpJsonChannelProvider;
 import com.google.api.gax.rpc.ApiClientHeaderProvider;
 import com.google.api.gax.rpc.ClientContext;
 import com.google.api.gax.rpc.ClientSettings;
@@ -327,11 +328,18 @@ public static GoogleCredentialsProvider.Builder defaultCredentialsProviderBuilde
     return DatastreamStubSettings.defaultCredentialsProviderBuilder();
   }
 
-  /** Returns a builder for the default ChannelProvider for this service. */
+  /** Returns a builder for the default gRPC ChannelProvider for this service. */
   public static InstantiatingGrpcChannelProvider.Builder defaultGrpcTransportProviderBuilder() {
     return DatastreamStubSettings.defaultGrpcTransportProviderBuilder();
   }
 
+  /** Returns a builder for the default REST ChannelProvider for this service. */
+  @BetaApi
+  public static InstantiatingHttpJsonChannelProvider.Builder
+      defaultHttpJsonTransportProviderBuilder() {
+    return DatastreamStubSettings.defaultHttpJsonTransportProviderBuilder();
+  }
+
   public static TransportChannelProvider defaultTransportChannelProvider() {
     return DatastreamStubSettings.defaultTransportChannelProvider();
   }
@@ -341,11 +349,17 @@ public static ApiClientHeaderProvider.Builder defaultApiClientHeaderProviderBuil
     return DatastreamStubSettings.defaultApiClientHeaderProviderBuilder();
   }
 
-  /** Returns a new builder for this class. */
+  /** Returns a new gRPC builder for this class. */
   public static Builder newBuilder() {
     return Builder.createDefault();
   }
 
+  /** Returns a new REST builder for this class. */
+  @BetaApi
+  public static Builder newHttpJsonBuilder() {
+    return Builder.createHttpJsonDefault();
+  }
+
   /** Returns a new builder for this class. */
   public static Builder newBuilder(ClientContext clientContext) {
     return new Builder(clientContext);
@@ -383,6 +397,11 @@ private static Builder createDefault() {
       return new Builder(DatastreamStubSettings.newBuilder());
     }
 
+    @BetaApi
+    private static Builder createHttpJsonDefault() {
+      return new Builder(DatastreamStubSettings.newHttpJsonBuilder());
+    }
+
     public DatastreamStubSettings.Builder getStubSettingsBuilder() {
       return ((DatastreamStubSettings.Builder) getStubSettings());
     }

google-cloud-datastream/src/main/java/com/google/cloud/datastream/v1/stub/DatastreamStub.java

@@ -86,7 +86,11 @@
 public abstract class DatastreamStub implements BackgroundResource {
 
   public OperationsStub getOperationsStub() {
-    throw new UnsupportedOperationException("Not implemented: getOperationsStub()");
+    return null;
+  }
+
+  public com.google.api.gax.httpjson.longrunning.stub.OperationsStub getHttpJsonOperationsStub() {
+    return null;
   }
 
   public UnaryCallable<ListConnectionProfilesRequest, ListConnectionProfilesPagedResponse>

google-cloud-datastream/src/main/java/com/google/cloud/datastream/v1/stub/DatastreamStubSettings.java

@@ -34,6 +34,9 @@
 import com.google.api.gax.grpc.GrpcTransportChannel;
 import com.google.api.gax.grpc.InstantiatingGrpcChannelProvider;
 import com.google.api.gax.grpc.ProtoOperationTransformers;
+import com.google.api.gax.httpjson.GaxHttpJsonProperties;
+import com.google.api.gax.httpjson.HttpJsonTransportChannel;
+import com.google.api.gax.httpjson.InstantiatingHttpJsonChannelProvider;
 import com.google.api.gax.longrunning.OperationSnapshot;
 import com.google.api.gax.longrunning.OperationTimedPollAlgorithm;
 import com.google.api.gax.retrying.RetrySettings;
@@ -863,6 +866,11 @@ public DatastreamStub createStub() throws IOException {
         .equals(GrpcTransportChannel.getGrpcTransportName())) {
       return GrpcDatastreamStub.create(this);
     }
+    if (getTransportChannelProvider()
+        .getTransportName()
+        .equals(HttpJsonTransportChannel.getHttpJsonTransportName())) {
+      return HttpJsonDatastreamStub.create(this);
+    }
     throw new UnsupportedOperationException(
         String.format(
             "Transport not supported: %s", getTransportChannelProvider().getTransportName()));
@@ -895,30 +903,56 @@ public static GoogleCredentialsProvider.Builder defaultCredentialsProviderBuilde
         .setUseJwtAccessWithScope(true);
   }
 
-  /** Returns a builder for the default ChannelProvider for this service. */
+  /** Returns a builder for the default gRPC ChannelProvider for this service. */
   public static InstantiatingGrpcChannelProvider.Builder defaultGrpcTransportProviderBuilder() {
     return InstantiatingGrpcChannelProvider.newBuilder()
         .setMaxInboundMessageSize(Integer.MAX_VALUE);
   }
 
+  /** Returns a builder for the default REST ChannelProvider for this service. */
+  @BetaApi
+  public static InstantiatingHttpJsonChannelProvider.Builder
+      defaultHttpJsonTransportProviderBuilder() {
+    return InstantiatingHttpJsonChannelProvider.newBuilder();
+  }
+
   public static TransportChannelProvider defaultTransportChannelProvider() {
     return defaultGrpcTransportProviderBuilder().build();
   }
 
   @BetaApi("The surface for customizing headers is not stable yet and may change in the future.")
-  public static ApiClientHeaderProvider.Builder defaultApiClientHeaderProviderBuilder() {
+  public static ApiClientHeaderProvider.Builder defaultGrpcApiClientHeaderProviderBuilder() {
     return ApiClientHeaderProvider.newBuilder()
         .setGeneratedLibToken(
             "gapic", GaxProperties.getLibraryVersion(DatastreamStubSettings.class))
         .setTransportToken(
             GaxGrpcProperties.getGrpcTokenName(), GaxGrpcProperties.getGrpcVersion());
   }
 
-  /** Returns a new builder for this class. */
+  @BetaApi("The surface for customizing headers is not stable yet and may change in the future.")
+  public static ApiClientHeaderProvider.Builder defaultHttpJsonApiClientHeaderProviderBuilder() {
+    return ApiClientHeaderProvider.newBuilder()
+        .setGeneratedLibToken(
+            "gapic", GaxProperties.getLibraryVersion(DatastreamStubSettings.class))
+        .setTransportToken(
+            GaxHttpJsonProperties.getHttpJsonTokenName(),
+            GaxHttpJsonProperties.getHttpJsonVersion());
+  }
+
+  public static ApiClientHeaderProvider.Builder defaultApiClientHeaderProviderBuilder() {
+    return DatastreamStubSettings.defaultGrpcApiClientHeaderProviderBuilder();
+  }
+
+  /** Returns a new gRPC builder for this class. */
   public static Builder newBuilder() {
     return Builder.createDefault();
   }
 
+  /** Returns a new REST builder for this class. */
+  public static Builder newHttpJsonBuilder() {
+    return Builder.createHttpJsonDefault();
+  }
+
   /** Returns a new builder for this class. */
   public static Builder newBuilder(ClientContext clientContext) {
     return new Builder(clientContext);
@@ -1272,6 +1306,19 @@ private static Builder createDefault() {
       return initDefaults(builder);
     }
 
+    private static Builder createHttpJsonDefault() {
+      Builder builder = new Builder(((ClientContext) null));
+
+      builder.setTransportChannelProvider(defaultHttpJsonTransportProviderBuilder().build());
+      builder.setCredentialsProvider(defaultCredentialsProviderBuilder().build());
+      builder.setInternalHeaderProvider(defaultHttpJsonApiClientHeaderProviderBuilder().build());
+      builder.setEndpoint(getDefaultEndpoint());
+      builder.setMtlsEndpoint(getDefaultMtlsEndpoint());
+      builder.setSwitchToMtlsEndpointAllowed(true);
+
+      return initDefaults(builder);
+    }
+
     private static Builder initDefaults(Builder builder) {
       builder
           .listConnectionProfilesSettings()